Brake system

ABSTRACT

A brake system for a vehicle having an axle set of brakes adapted for energization in response to spring setting pressure released brake actuators connected therewith is provided with an operator actuated application valve for selectively venting fluid pressure from said brake actuators to effect spring set energization of said axle set of brakes, and an emergency brake valve is also responsive to the selective venting of the fluid pressure from said brake actuators to apply fluid pressure to the other axle set of brakes of said vehicle and effect fluid pressure energization thereof. The emergency brake valve is provided with valve means for controlling the application of fluid pressure therethrough, and a resiliently urged member responsive to control fluid pressure less than a predetermined value for actuating said valve means.

United States Patent 1 Cruse July 17, 1973 BRAKE SYSTEM PrimaryExaminer-Allen N. Knowles [75] Inventor: Oliver B. Cruse, Florissant,Mo, Amman hxammerGen.e Church Attorney-Joseph E. Papin [73] Assignee:Wagner Electric Corporation,

Newark, NJ. 57 ABSTRACT [22] Filed: Apr. 3, 1972 A brake system foravehicle having an axle set of Appl. No; 240,456

Related US. Application Data brakes adapted for energization :inresponse to spring setting pressure released brake actuators connectedtherewith is provided with an operator actuated application valve forselectively venting fluid pressure from said brake actuators to effectspring set energization of said axle set of brakes, and an emergencybrake valve is also responsive to the selective venting of the fluidpressure from said brake actuators to apply fluid pressure to the otheraxle set of brakes of said vehicle and effect fluid pressureenergization thereof. The emergency brake valve is provided with valvemeans for controlling the application of fluid pressure there through,and a resiliently urged member responsive to control fluid pressure lessthan a predetermined value for actuating said valve means.

16 Claims, 3 Drawing Figures BRAKE SYSTEM This application is a divisionof co-pending application Ser. No. 117,958 filed Feb. 23, 1971.

This invention relates in general to vehicle brake systems and inparticular to such systems utilizing spring set brake actuators andemergency brake valves for controlling a portion of such system.

SUMMARY In the past dual braking systems, spring setting pressurereleased brake actuators of a type well-known in the art were utilizedto energize the rear axle set of brakes on trucks, tractors of atractor-trailer train, or other like vehicles. For instance, in theevent of a fluid pressure failure in the service portion of the dualsystem, it was possible for the vehicle operator to meter emergencyfluid pressure from the spring setting pressure released brake actuatorsto effect a spring set energization of the rear axle set of brakes underthese emergency conditions to stop the vehicle. One of thedisadvantageous or undesirable features of such past brake system wastheir inability to utilize the front axle set of vehicle brakes toeffect the vehicle stop under such emergency conditions since such frontaxle brakes were energized by the service portion of the system.

The primary object of the present invention is to provide a brake systemand an emergency brake valve for train, or other such vehicles having afront axle brake set 2-2a and a rear axle brake set 3 controlled byspring setting pressure released brake cylinders or actuators 4 of atype well-known in the art and including emergency or spring setportions 5 and service or fluid pressure responsive motors 6 forenergizing the rear brakes; however, for the sake of expediency only onerear axle brake 3 and spring set actuator 4 therefor is shown.

A reservoir or source of service fluid pressure 7 is fed from acompressor (not shown) and connected with an other reservoir or sourceof emergency fluid pressure 8 by a conduit 9 having a uni-directionalflow or check use therein which overcomes the aforementioned dis- 7advantageous or undesirable features of the pastbrake systems, and this,as well as other objects and advantageous features of the presentinvention, will become apparent hereinafter.

Briefly, the presentinvention comprises a brake system having a pair ofbrakes, one of which is spring set energized by a spring settingpressure released actuator generally operable in response to fluidpressure supplied "thereto less than a predetermined value, and othermeans responsive to the supplied fluid pressure less than thepredetermined value for applying fluid pressure to effect energizationof the other of said brakes. The invention also includes a control valvehaving resiliently urged means responsive to acontrol fluid pressureless than a predetermined value for effecting the application throughsaid control valve of operating fluid pressure.

RELATED PATENTS This patent application is related generally to theRichard C. Bueler U.S. Pat. No. 3,309,149 issued Mar. 14, 1967, the H.M. Valentine et a]. U.S. Pat. No.

3,504,946 issued Apr. 7, 1970, and the Oliver B. Cruse U.S. Pat. No.3,533,661 issued Oct. l3, 1970; however, this present patent applicationis apatentably distinct improvement.

DESCRIPTION OF THE DRAWINGS is shown for use on a truck, a tractor of atractor-trailer valve 10 interposed therein, and said service andemergency sources are connected to the inlet sides of serviceandemergency portions 11, 12 of a dual application valve 13 by conduits14, 15, respectively. The application valve 13 may be of the typedisclosed in my U.S. Pat. No. 3,533,661 issued Oct. 13, 1970 or of thetype shown in the Richard C. Bueler U.S. Pat. No. 3,309,149 issued Mar.14, 1967 The outlet side of the application valve service portion ll isconnected through a two way check valve 1 6 by a conduit 17 to anotherconduit 18 which branches to connect with fluid pressure responsivemotors or brake chambers 19, 19a, and said brake chambers areoperatively connected by suitable means well-known in the art (notshown) with the front axle brakes 2, 2a to effect energization thereof.Conduit 20 has one end connected to the conduit 17 between the outletside of the application valve service portion 11 and the two way checkvalve 16 while the other end thereof is connected with the service orfluid pressure responsive motor portion 6 of the spring set actuator 4,and another conduit 21 is connected between the outlet side of theapplication valve emergency portion 12 and the emergency or springsetting portion 5 of the spring set actuator 4. To complete thedescription of the system 1, the inlet and outlet ports of an emergencybrake or control valve 22 are respectively connected with conduits 23,23a which are, in turn, respectively connected with emergency reservoir8 and the two way valve 16, and a control conduit 24 is connectedbetween the conduit 21 and the control port of said emergency brakevalve.

The control or emergency brake valve 22 is provided with upper and lowerhousings 25, 26 having a seal connected by suitable means such as studs28. The upper housing is provided with an integral, radially extendingwall portion 29 adjacent to its lower or interior end 30, and upper andlower counterbores 31, 32 areprovided in said housing25 beinginterconnected by a bore 33 extending through said wall portion. Aclosure member 34 is connected to the upper end of the housing 25 bysuitable means such as studs 35 closing the open end of the counterbore31, and a control or supply port 36, which receives the conduit 24 aspreviously mentioned, is providedtin the housing 25 intersecting withthe counterbore 31 adjacent tothe wall 29, Application or resilientlyurged means, such as interconnected piston members 37, 38 are slidablyreceived in the counterbores 31, 32, and carry'peripheral seals 39, 40in sealing engagement with said counterbores, re-

spectively. An expansible fluid pressure or control chamber, is definedin the counterbore .31 between the housing wall 29 and piston 37connected in pressure fluid communication with the control port 36 atall times, andan emergency or meteringspring 42 is precompressed betweensaid piston andthe closurememher 34 opposing fluid pressure expansion ofsaid chamber. An aperture 43 is centrally provided in the piston 37which sealably receives the upper or connecting end portion 44 of anextension 45 provided on the piston 38, and the piston 38 is fixedlyconnected with the piston 37 by suitable means, such as the nut 46 whichis threadedly received on said end portion. The extension 45 is slidablein the housing bore 33 carrying a peripheral seal 47 in sealingengagement with said housing bore, and the piston 38 is also providedwith an opposing extension 48 having a free end therein defining a valveseat 49, to be discussed hereinafter.

The housing 26 is provided with a bore 50 defining an outlet chamberinto which the lower end 30 of the housing 25 extends coaxially, and apassage 51 is provided in the housing 26 between said bore and an inletchamber 52. Inlet and outlet ports 53, 54, which re ceive the conduits23, 23a, as previously mentioned, are provided in the housing 26connecting with the bore 50 and the inlet chamber 52, respectively, anda I the inlet chamber 52 and said valve member. The valve member 59 isprovided with an exhaust passage or opening 62 therethrough normallyproviding pressure fluid communication between the outlet chamber andport 50, 54 and the atmosphere, and an annular resilient seal or disc 63is provided on the upper end of said valve member in circumscribingrelation with said exhaust passage. A valve spring 64 is biased betweenthe valve guide 56 and the valve member 59 normally urging the valvemember seal 63 into sealing engagementwith'the housing valve seat 55 tointerrupt pressure fluid communication between the inlet and outletports 53, 54. To complete the description of the control valve 22, itshould be noted that the pistons 37, 38 are provided with additive areasA,, A, which are subjected to fluid pressures in the controland outletchambers 41, 50, respectively. I

In the operation of the system 1, assuming that the service reservoir 7is fully charged from the compressor (not shown), the fluid pressureflows therefrom through the conduit 9 and check valve into the emergencyreservoir 8 and therefrom through the conduit to the inlet side of theapplication valve emergency portion 12. Normally the application valveemergency portion [2 establishes pressure fluid communication betweenthe inlet and outlet sides thereof in response to the emergency fluidpressure to transmit a supplied or control emergency fluid pressure fromthe conduit 15 through the conduit 21 to the brake actuator 4 in orderto disable the emergency spring setting portion 5 thereof. The suppliedor control emergency fluid pressure in the conduit 21 also flows throughthe conduit 24 andcontrol port 36 of the control valve 22 into thecontrol chamber 41 acting on the effective area A of the piston 37 toestablish a force F to urge the pistons 37, 38 toward their inoperativepositions, as shown in FIG. 2, against the compressive force of thespring 42.

In order to effect a normal service braking application, the operatorapplies a manual force on the application valve 13 to actuate theservice portion 11 thereof which effects the application of fluidpressure from the service reservoir 7 through the conduits 14, 17, thetwo way check valve 16, and the conduit 18 to actuate the front brakechambers 19, 19a and energize the front brakes 2, 20. At the same time,the applied service fluid pressure also flows from the conduit 17through the conduit 20 to actuate the service motor portion 6 of therear brake actuator 4 and effect service energization of the rear brakes3 substantially simultaneously with the service energization of thefront brakes 2, 2a. When the desired service braking vehicledeceleration or complete stop is effected, the operator applied force isremoved from the application valve 13 wherein the service portion 11thereof again isolates the service reservoir 7 and vents the appliedservice fluid pressure from the brake chambers 19, through the conduit18, the two way check valve 16, the conduit 17 and said applicationvalve service portion to the atmosphere thereby de-energizing the frontbrakes 2, 20. At the same time, the applied service fluid pressure isalso vented from the service motor portion 6 of the rear brake actuator4 through the conduit 26 and the application valve service portion 12 todeenergize the rear brakes 3.

In the event of a fluid pressure failure in the service reservoir 7, itshould be noted that the integrity of the emergency reservoir 8 ispreserved by the check valve 10. Under these emergency conditions ofservice fluid pressure failure, the operator applies a manual force onthe application valve 13 to actuate the emergency portion 12 thereofwhich initially isolates the inlet side thereof and the emergencyreservoir 8 from the outlet side thereof and thereafter vents thesupplied emergency fluid pressure from the emergency spring set portion5 of the rear brake actuator 4 through the conduit 21 and saidapplication valve emergency portion to the atmosphere. When the suppliedemergency fluid pressure at the emergency spring set portion 5 of therear brake actuator 4 is so reduced to a predetermined value, the springsetting portion 5 of said brake actuator is actuated and effects aspring set-energization of the rear brakes 3. Of course, theaforementioned venting of the supplied emergency fluid pressure by theapplication valve emergency portion 12 also effects simultaneous ventingof the supplied emergency fluid pressure from the control chamber 41 ofthe control valve 22 through the control port 36 thereof and the conduit24. When the emergency fluid pressure in the control chamber 41 isthereby also reduced to the predetermined value, the compressive forceof the spring 42 overcomes the opposing control force F, to urge thepistons 37, 38 downwardly from their inoperative position toward anoperative position to initially engage the valve seat 49 of the piston38 with the valve member 59 closing the exhaust passage 62 thereof toisolate the outlet chamber and port 50, 54 from the'atmosphere andthereafter move said valve member toward an open position disengagedfrom the housing valve seat 55 to establish metered pressure fluidcommunication between the inlet and outlet ports 53, 54. In this manneremergency fluid pressure is applied or metered directly from theemergency reservoir 8 through the conduit 23, the' inlet chamber andport 52, 53 of the control valve 22, the passage 51 and the outletchamber and port 50, 54, the conduit 23a, the two way valve 16 and theconduit 18 to actuate the front brake chambers 19, 19a and effectemergency fluid pressure energization of the front brakes 2, 2asubstantially simultaneously with the emergency energization of the rearbrakes 3. The applied emergency fluid pressure so established in theoutlet chamber 50 of the control valve 22 acts on the effective area Aof the piston 38 to establish another force F which is additive to theforce F, to oppose further movement of the pistons 37, 38 in response tothe compressive force of the emergency spring 42 acting thereon, andwhen the additive forces F F attain a value equal to the compressiveforce of the emergency spring 42, the pistons 37, 38 are moved upwardlyagainst said spring untilthe valve member 59 is positioned in lappedengagement with the housing valve seat 55 and the piston valve seat 49.Of course, if greater emergency braking isdesired, the manual force onthe application valve emergency portion 12 is increased to effectfurther venting of the supplied emergency fluid pressure from the springsetting portion of the rear brake actuator 4 and the control valve 22 tothe atmosphere, and the component parts of the system l and controlvalve 22 function in the same manner, as above described.

When the desired emergency braking effect is attained under theemergency conditions, the manually applied force is removed from theapplication valve 13 causing the emergency portion 12 thereof toinitially interrupt the pressure fluid communication between theatmosphere and conduits 20, 24 and thereafter reestablish pressure fluidcommunication between the emergency reservoir 8 and said conduits toagain supply emergency fluid pressure in excess of the predeterminedvalue from said emergency reservoir through the conduit 15, saidapplication valve emergency portion and the conduit 21 into the brakeactuator 4 to again disable the spring setting portion 5 thereof andeffect a de-energization of the rear brakes 3. At the same time thesupplied emergency fluid pressure in excess of the predetermined valuealso flows from the conduit 21 through the conduit 24 and the controlport 36 of the control valve 22 into the control chamber 41 thereof tore-establish the force F,. Upon the reestablished force F,, the pistons37, 38 are moved upwardly thereby toward their inoperative positionagainst the compressive force of the emergency spring 42, and in thismanner the valve seat 49 is disengaged from the valve member 59 to openthe valve member exhaust passage 62 and effect the exhaustion of theapplied emergency fluid pressure from the front brake actuators 19, 19athrough the conduit 18, the two way valve 16, the conduit 23a, thecontrol valve outlet port 54 and outlet chamber 50 and said valve memberexhaust passage to the atmosphere thereby effecting de-energization ofthe front brakes 2, 2a substantially simultaneously with thede-energization of the rear brakes 3. Of course, the venting of theapplied emergency fluid pressure to the atmosphere eliminates the forceF from the piston 38.

In the event that the emergency fluid pressure'in the emergency tank 8is depleted to a value less than the predetermined value due to systemactuation or leaks or the like, the spring setting portion 5 of the rearbrake actuator 4 and the control valve 22 will function, as abovedescribed, to effect the emergency energization of the front and rearbrakes 2, 2a and 3.

Referringnow to'FlG. 3, a fluid pressure system 101 is shown havingsubstantially the same component parts and-functioning in substantiallythe same manner as the previously described system 1 withthe followingexceptions: In the system 101, another reservoir or source of emergencyfluid pressure 102 is connected with-the service reservoir 7 by aconduit 103 having a uni-directional or check valve 104 interposedtherein, and another conduit 105 is connected between the emergencyreservoir 102 and the inlet port 53 of the control valve 22. In thismanner, the check valve 104 preserves the fluid pressure integrity ofthe emergency reservoir 102 in the event of the depletion of fluidpressure in the emergency reservoir 8, as discussed hereinabove;therefore, full system pressure is always. available for applicationfrom the emergency reservoir 102 through the conduit 105, the controlvalve 22, the conduit 23a, the two way check valve 16, and the conduit18 to actuate the front brake chambers 19, 19a and effect emergencyfluid pressure energization of the front brakes 2, 2a.

While front and rear brakes 2, 2a and 3 and front and rear brakeactuators 19, 19a and 4 therefor have been discussed therein, it isobvious that such brakes and brake actuators can be employed on the rearaxles of a tandem axle vehicle, and such use is contemplated by theinvention.

It is now apparent that novel fluid pressure systems 1, 101 and acontrol valve 22 therefor meeting the objects and advantages set outhereinbefore, as well as other objects and advantages apparent from thedisclo sure, are provided and that changes in the mode of operation orthe precise configurations, shapes or details of the constructions setforth in the disclosure by way of illustration may be made by thoseskilled in the art without departing from the spirit of the invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

l. A fluid pressure system comprising a pair of brakes, a pair of fluidpressure sources, means for energizing said brakes in response to fluidpressure selectively applied thereto from one of said sources, a springsetting pressure released brake actuator connected with one of saidbrakes and operable in response to fluid pressure supplied thereto lessthan a predetermined value from the other of said sources to effectspring set energization of said one brake, and other means responsive tothe fluid pressure less than the predetermined value supplied from saidother source to said brake actuator for applying fluid pressure fromsaid other source to the other of said brakes to also ef fectenergization thereof.

2. A fluid pressure system comprising a pair of brakes, apair of fluidpressure sources, first means responsive to fluid pressure selectivelyapplied thereto from one of said sources for energizing at least one ofsaid brakes, second means responsive to fluid pressure supplied theretofrom the other of said sources less than a predetermined value forenergizing the other of said brakes, and third means for applying fluidpressure from said other source tosaid first means to effectenergization of said one brake in the event the supplied fluid pressureis reduced to a value less than the predetermined value.

3. A, fluid pressure system comprising a pair of brakes, a pair ofmotors for energizing said brakes, a

pair of fluid pressure sources, a spring setting pressure released brakeactuator connected with one of said brakes, means for applying fluidpressure from said sources to said motors effecting energization of saidbrakes and to said brake actuator, respectively, and for venting thefluid pressure applied to said brake actuator to the atmosphere underpreselected conditions, said brake actuator being responsive to thefluid pressure applied thereto less than a predetermined value to effectspring set energization of one of said brakes, and other means forapplying fluid pressure from one of said sources to one of said motorsto energize the other of said brakes in response to the reduction of thefluid pressure applied to said brake actuator to a value less than thepredetermined value.

4. A fluid pressure system according to claim 3,

wherein said other means includes application means controlling pressurefluid communication between said one source and said one motor, saidapplication means being movable in response to fluid pressure applied tosaid brake actuator less than the predetermined value toward anoperative position communicating said one source and said one motor.

5. A fluid pressure system comprising a pair of brakes, a pair of motorsfor energizing said brakes, a pair of fluid pressure sources, a springsetting pressure released brake actuator connected with one of saidbrakes, means for applying fluid pressure from said sources to said'motors effecting energization of said brakes and to said brakeactuator, respectively, and for venting the fluid pressure applied tosaid brake actuator to the atmosphere under preselected conditions, saidbrake actuator being responsive to the fluid pres sure applied theretoless than a predetermined value to effect spring set energization of oneof said brakes, other means for applying fluid pressure from one of saidsources to one of said motors to energize the other of said brakes inresponse to the reduction of the fluid pressure applied to said brakeactuator to a value less than the predetermined value, said other meansincluding application means controlling pressure fluid communicationbetween said one source and said one motor, said application means beingmovable in response to fluid pressure applied to said brake actuatorless than the predetermined value toward an operative positioncommunicating said one source and said one motor, and said applicationmeans including resiliently urged means, an area on said resilientlyurged means subjected to the fluid pressure applied to said brakeactuator, said resiliently urged means being movable against its oneforce in response to the fluid pressure applied to said brake actuatorin excess of the predetermined value acting on said area toward aninoperative position isolating said one source from said one brake andbeing movable toward its operative position in the event the fluidpressure applied to said brake actuator and acting on said area isreduced to a value less than the predetermined value.

6. A fluid pressure system according to claim 5,

I wherein said resiliently urged means includes piston means, said areabeing on said piston means, and spring means urging said piston meanstoward the operative position thereof.

7. A fluid pressure system according to claim 5, comprising another areaon said resiliently urged means additive to said first named area andsubjected to the fluid pressure applied from said one source to said onemotor.

8. A fluid pressure system according to claim 7, wherein said firstnamed area is predeterminately greater than said other area.

9. A fluid pressure system according to claim 7, wherein saidapplication means includes resiliently urged means, an area on saidresiliently urged means subjected to the supplied fluid pressure, saidresiliently urged means being movable in response to its own forcetoward the operative position in said flow passage when the suppliedfluid pressure acting on said area is less than the predetermined value.

10. A fluid pressure system according to claim 9, wherein saidresiliently urged means includes piston means, said area being on saidpiston means, and spring means urging said piston means toward itsoperative position.

11. A fluid pressure system according to claim 10, wherein said pistonmeans is movable toward an inoperative position against said springmeans in response to the supplied fluid pressure in excess of thepredetermined value acting on said area, valve means for engagement withsaid piston means controlling said flow passage, said piston means beingmovable in response to said spring means when the supplied fluidpressure acting on said area is less than the predetermined value towardthe operative position to engage and actuate said valve means and effectthe application through said flow passage of the fluid pressure fromsaid other source to said first means.

12. A fluid pressure system according to claim 10, wherein said thirdmeans includes a valve seat about said flow passage, said valve meansbeing urged into engagement with said valve seat to close said flowpassage when said piston means is in its inoperative position, saidvalve means being actuated by said piston means upon the movementthereof toward the operative position and disengaged from said valveseat.

13. A fluid pressure system comprising a pair of brakes, a pair of fluidpressure sources, first means responsive to fluid pressure selectivelyapplied thereto from one of said sources for energizing at least one ofsaid brakes, second means responsive to fluid pressure supplied theretofrom the other of said sources less than a predetermined value forenergizing the other of said brakes, third means for applying fluidpressure from said other source to said first means to effectenergization of said one brake in the event the supplied fluid pressureis reduced to a value less than the predetermined value, said thirdmeans including a pressure fluid flow passage connected between saidother source and said first means, and application means for controllingsaid fl0w passage, said application means being movable in response tothe supplied fluid pressure less than the predetermined value toward anoperative position in said flow passage effecting the application therethrough of the fluid pressure from said other source to said firstmeans.

14. A fluid pressure system according to claim 13, comprising valvemeans controlling said flow passage, said valve means being actuated bysaidapplication means upon the movement thereof to its operativeposition to effect the application through said flow passage of thefluid pressure from said other source to said first named means.

15. A fluid pressure system according to claim 11, wherein said thirdmeans includes a valve seat about said flow passage, said valve meansbeing normaly urged into engagement with said valve seat to close saidflow passage and interrupt pressure fluid communication between saidother source and said first means, said valve means being disengagedfrom said valve seat to establish the pressure fluid communicationbetween said other source and said first means upon the actuation ofsaid valve means by said application means.

16. A fluid pressure system comprising a pair of brakes, a source ofservice pressure, a source of emergency pressure, a pair of servicemotors connected with said brakes, a spring setting pressure releasedbrake actuator also connected with one of said brakes, an operatoractuated application valve having service and emergency portionsrespectively connected with said service and emergency pressure sourcesincluding first means in said service portion selectively movable uponoperator actuation of said application valve to effect the applicationof service pressure from the source thereof to said service motors forenergizing said brakes, and second means in said emergency portionnormally applying emergency fluid pressure from the source thereof tosaid brake actuator and movable to isolate said emergency pressuresource from said brake actuator and vent the emergency pressure fromsaid brake actuator to the atmosphere under preselected conditions, saidbrake actuator being responsive to the reduction of the emergencypressure therefrom to a predetermined value to effect spring setenergization of said one brake, an emergency brake valve including ahousing, a flow passage in said housing connected between said emergencypressure source and one of said service motors, valve means controllingsaid flow passage, a chamber in said housing connected with theemergency fluid pressure supplied to said actuator and separate fromsaid flow passage, a valve actuating member movable in said chamberincluding a stem portion extending into said flow passage for operativeen-,

gagement with said valve means, spring means engaged with said valveactuating member and opposing fluid pressure expansion of said chamber,an area on said valve actuating member subjected to the emergency fluidpressure in said chamber, said valve actuating member being movableagainst the force of said spring means in response to the emergencyfluid pressure on said chamber in excess of a predetermined value actingon said area and said valve actuating member also being movable inresponse to the force of said spring means when the emergency fluidpressure in said chamber acting on said area is reduced to a value lessthan the predetermined value to engage said stem portion with said valvemeans and move said valve means toward a position in said flow passageeffecting the application therethrough of the emergency pressure fromthe source thereof to said one service motor for energizing the other ofsaid brakes, and another area on said stem portion in said flow passageadditive'to said first named area and subjected to the emergencypressure applied therethrough to said one service motor to oppose theforce of said spring means.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION patent 3 746 ,400Dated July 17, 1973 Inventor(s) ollver Cruse It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

Column 9,-.line l, "11" should read l4 line 3, "normaly" should readnormally Signed and sealed this 26th day-of March 1974.

(SEAL) Attest:

EDWARD M.PLETCHER,JR. C. MARSHALL DANN Attesting Officer Commissioner ofPatents FORM PC4050 (10-69) UscoMM Dc 60376 P69 u.s. GOVERNMENT PRINTINGOFFICE: 1919 oacs-s:4.

1. A fluid pressure system comprising a pair of brakes, a pair of fluidpressure sources, means for energizing said brakes in response to fluidpressure selectively applied thereto from one of said sources, a springsetting pressure released brake actuator connected with one of saidbrakes and operable in response to fluid pressure supplied thereto lessthan a predetermined value from the other of said sources to effectspring set energization of said one brake, and other means responsive tothe fluid pressure less than the predetermined value supplied from saidother source to said brake actuator for applying fluid pressure fromsaid other source to the other of said brakes to also effectenergization thereof.
 2. A fluid pressure system comprising a pair ofbrakes, a pair of fluid pressure sources, first means responsive tofluid pressure selectively applied thereto from one of said sources forenergizing at least one of said brakes, second means responsive to fluidpressure supplied thereto from the other of said sources less than apredetermined value for energizing the other of said brakes, and thirdmeans for applying fluid pressure from said other source to said firstmeans to effect energization of said one brake in the event the suppliedfluid pressure is reduced to a value less than the predetermined value.3. A fluid pressure system comprising a pair of brakes, a pair of motorsfor energizing said brakes, a pair of fluid pressure sources, a springsetting pressure released brake actuator connected with one of saidbrakes, means for applying fluid pressure from said sources to saidmotors effecting energization of said brakes and to said brake actuator,respectively, and for venting the fluid pressure applied to said brakeactuator to the atmosphere under preselected conditions, said brakeactuator being responsive to the fluid pressure applied thereto lessthan a predetermined value to effect spring set energization of one ofsaid brakes, and other means for applying fluid pressure from one ofsaid sources to one of said motors to energize the other of said brakesin response to the reduction of the fluid pressure applied to said brakeactuator to a value less than the predetermined value.
 4. A fluidpressure system according to claim 3, wherein said other means includesapplication means controlling pressure fluid communication between saidone source and said one motor, said application means being movable inresponse to fluid pressure applied to said brake actuator less than thepredetermined value toward an operative position communicating said onesource and said one motor.
 5. A fluid pressure system comprising a pairof brakes, a pair of motors for energizing said brakes, a pair of fluidpressure sources, a spring setting pressure released brake actuatorconnected with one of said brakes, means for applying fluid pressurefrom said sources to said motors effecting energization of said brakesand to said brake actuator, respectively, and for venting the fluidpressure applied to said brake actuator to the atmosphere underpreselected conditions, said brake actuatOr being responsive to thefluid pressure applied thereto less than a predetermined value to effectspring set energization of one of said brakes, other means for applyingfluid pressure from one of said sources to one of said motors toenergize the other of said brakes in response to the reduction of thefluid pressure applied to said brake actuator to a value less than thepredetermined value, said other means including application meanscontrolling pressure fluid communication between said one source andsaid one motor, said application means being movable in response tofluid pressure applied to said brake actuator less than thepredetermined value toward an operative position communicating said onesource and said one motor, and said application means includingresiliently urged means, an area on said resiliently urged meanssubjected to the fluid pressure applied to said brake actuator, saidresiliently urged means being movable against its one force in responseto the fluid pressure applied to said brake actuator in excess of thepredetermined value acting on said area toward an inoperative positionisolating said one source from said one brake and being movable towardits operative position in the event the fluid pressure applied to saidbrake actuator and acting on said area is reduced to a value less thanthe predetermined value.
 6. A fluid pressure system according to claim5, wherein said resiliently urged means includes piston means, said areabeing on said piston means, and spring means urging said piston meanstoward the operative position thereof.
 7. A fluid pressure systemaccording to claim 5, comprising another area on said resiliently urgedmeans additive to said first named area and subjected to the fluidpressure applied from said one source to said one motor.
 8. A fluidpressure system according to claim 7, wherein said first named area ispredeterminately greater than said other area.
 9. A fluid pressuresystem according to claim 7, wherein said application means includesresiliently urged means, an area on said resiliently urged meanssubjected to the supplied fluid pressure, said resiliently urged meansbeing movable in response to its own force toward the operative positionin said flow passage when the supplied fluid pressure acting on saidarea is less than the predetermined value.
 10. A fluid pressure systemaccording to claim 9, wherein said resiliently urged means includespiston means, said area being on said piston means, and spring meansurging said piston means toward its operative position.
 11. A fluidpressure system according to claim 10, wherein said piston means ismovable toward an inoperative position against said spring means inresponse to the supplied fluid pressure in excess of the predeterminedvalue acting on said area, valve means for engagement with said pistonmeans controlling said flow passage, said piston means being movable inresponse to said spring means when the supplied fluid pressure acting onsaid area is less than the predetermined value toward the operativeposition to engage and actuate said valve means and effect theapplication through said flow passage of the fluid pressure from saidother source to said first means.
 12. A fluid pressure system accordingto claim 10, wherein said third means includes a valve seat about saidflow passage, said valve means being urged into engagement with saidvalve seat to close said flow passage when said piston means is in itsinoperative position, said valve means being actuated by said pistonmeans upon the movement thereof toward the operative position anddisengaged from said valve seat.
 13. A fluid pressure system comprisinga pair of brakes, a pair of fluid pressure sources, first meansresponsive to fluid pressure selectively applied thereto from one ofsaid sources for energizing at least one of said brakes, second meansresponsive to fluid pressure supplied thereto from the other of saidsources less than a predetermined value for energizing the otHer of saidbrakes, third means for applying fluid pressure from said other sourceto said first means to effect energization of said one brake in theevent the supplied fluid pressure is reduced to a value less than thepredetermined value, said third means including a pressure fluid flowpassage connected between said other source and said first means, andapplication means for controlling said flow passage, said applicationmeans being movable in response to the supplied fluid pressure less thanthe predetermined value toward an operative position in said flowpassage effecting the application therethrough of the fluid pressurefrom said other source to said first means.
 14. A fluid pressure systemaccording to claim 13, comprising valve means controlling said flowpassage, said valve means being actuated by said application means uponthe movement thereof to its operative position to effect the applicationthrough said flow passage of the fluid pressure from said other sourceto said first named means.
 15. A fluid pressure system according toclaim 11, wherein said third means includes a valve seat about said flowpassage, said valve means being normaly urged into engagement with saidvalve seat to close said flow passage and interrupt pressure fluidcommunication between said other source and said first means, said valvemeans being disengaged from said valve seat to establish the pressurefluid communication between said other source and said first means uponthe actuation of said valve means by said application means.
 16. A fluidpressure system comprising a pair of brakes, a source of servicepressure, a source of emergency pressure, a pair of service motorsconnected with said brakes, a spring setting pressure released brakeactuator also connected with one of said brakes, an operator actuatedapplication valve having service and emergency portions respectivelyconnected with said service and emergency pressure sources includingfirst means in said service portion selectively movable upon operatoractuation of said application valve to effect the application of servicepressure from the source thereof to said service motors for energizingsaid brakes, and second means in said emergency portion normallyapplying emergency fluid pressure from the source thereof to said brakeactuator and movable to isolate said emergency pressure source from saidbrake actuator and vent the emergency pressure from said brake actuatorto the atmosphere under preselected conditions, said brake actuatorbeing responsive to the reduction of the emergency pressure therefrom toa predetermined value to effect spring set energization of said onebrake, an emergency brake valve including a housing, a flow passage insaid housing connected between said emergency pressure source and one ofsaid service motors, valve means controlling said flow passage, achamber in said housing connected with the emergency fluid pressuresupplied to said actuator and separate from said flow passage, a valveactuating member movable in said chamber including a stem portionextending into said flow passage for operative engagement with saidvalve means, spring means engaged with said valve actuating member andopposing fluid pressure expansion of said chamber, an area on said valveactuating member subjected to the emergency fluid pressure in saidchamber, said valve actuating member being movable against the force ofsaid spring means in response to the emergency fluid pressure on saidchamber in excess of a predetermined value acting on said area and saidvalve actuating member also being movable in response to the force ofsaid spring means when the emergency fluid pressure in said chamberacting on said area is reduced to a value less than the predeterminedvalue to engage said stem portion with said valve means and move saidvalve means toward a position in said flow passage effecting theapplication therethrough of the emergency pressure from the sourcethereof to said one service motor for energizing the other of saidbrakes, and another area on said stem portion in said flow passageadditive to said first named area and subjected to the emergencypressure applied therethrough to said one service motor to oppose theforce of said spring means.